Natural draft, fan-assisted natural draft and forced draft cooling towers are well known and commonly employed to withdraw waste heat from industrial plants and in particular to withdraw waste heat from condenser cooling liquid exhausting from steam and the like condensable fluid turbine driven power generating stations.
A number of different types of fan-assisted natural draft and natural draft cooling towers have been designed, constructed and used. In one common form, the filling or heat transfer sections are mounted within the chimney portion of the tower assembly on supporting framework. Above the filling or heat exchange sections are mounted a network or grid of liquid distribution pipes which direct the liquid to be cooled to the external surface of the filling. Below the filling and in the lower side walls of the tower are inlet openings for atmospheric air and the base of the tower comprises a sump for collection of the air-cooled liquid. Such assemblies may also include droplet or mist eliminators which are mounted above the network of liquid distribution pipes.
In such cooling towers, a liquid, generally water, comes into direct contact with an upward flow of atmospheric air in heat exchange relation with the water trickling over the outer surfaces of the fill. The fill generally comprises a series of even or corrugated plates or sheets, or of gratings of various forms.
Natural draft cooling towers of the type described above may be as high as from about 300 to 500 feet and the supporting framework for the fill for such a tower may have a height of from about 50 to 65 feet. Thus, the supporting framework for the heat exchange fill is sensitive to seismic movements and means must be taken into account when designing such structures to reduce to a minimum the adverse effects of potential seismic movements.